CHICAGO -- Lucas Giolito cruised through the first four innings of the White Sox 6-3 loss to the Cubs on Saturday before 38,634 at Guaranteed Rate Field.

But then the fifth inning came around, and things went south in a hurry for the White Sox All-Star.

• Box score

“I felt good. Got out of sync, and I didn’t correct it,” said Giolito of the five-spot he allowed to the National League Central leaders in the frame to break a 1-1 tie. “That’s what happened.

“I’m not worried about my year or anything. I’m very frustrated with this game, clearly. The loss is on me. It’s all on me. It was one inning where I got out of sync and couldn’t correct it. They took advantage.”

The loss gave the Cubs a 2-1 edge in the season series, keeping the Crosstown Cup on the North Side of town after the Cubs won the showdowns in each of the past two seasons.

Giolito topped the American League in walks with 90 last season, but he entered his last start of the first half with 33 free passes against 115 strikeouts over 96 innings pitched. In the fifth, Giolito walked the bases loaded, with free passes issued to Robel Garcia, David Bote and Addison Russell at the bottom of the order, and then gave up consecutive two-run doubles to Kyle Schwarber and Javier Baez.

Schwarber’s double was a spinner over third baseman Yoán Moncada, featuring an exit velocity of 56.6 mph and an expected batting average of .430.

“Schwarbs hit that ball and did not even know where it was,” Cubs manager Joe Maddon said. ”He really did not know. And then he took off and ran. That's kind of the big hit of the night. But, when you're facing a pitcher like Giolito, you've got to take advantage of everything, because his stuff is that outstanding. And we did.”

“They got some timely knocks to put those runs on the board,” White Sox manager Rick Renteria said. “We took him out of there trying to minimize the damage, but yeah, I do think he did lose his release point a little bit.”

Eight straight Cubs reached base in that fifth before Jace Fry curtailed the damage in five pitches by striking out Jason Heyward with the bases loaded and nobody out and inducing a double-play grounder from Garcia. Giolito allowed six runs on four hits and a season-high five walks, while striking out five in four-plus innings. He induced 21 swinging strikes over 87 pitches.

Featuring a 3.15 ERA overall this season, that Giolito number includes a 12.96 ERA in 8 1/3 innings pitched during two starts against the Cubs (12 earned runs allowed) and a 2.26 ERA in 91 2/3 innings pitched vs. everyone else. Giolito identified his front side flying open as the possible problem, something taking place when he walked Anthony Rizzo to start the fourth. He was able to fix the issue out of the stretch in the fourth, but not the ensuing inning.

“Usually when you try harder, it makes it worse. I probably did that,” Giolito said. “I don’t know. I don’t have a great explanation right now. I’m going to have to look at it.

“In that one [inning], it just kept going. I didn’t make the adjustment, losing too many pitches with bad misses. You walk the bases loaded with zero outs and you’re inviting some bad stuff to happen.”

Fry, Juan Minaya, Josh Osich and José Ruiz held the Cubs scoreless over five innings and allowed the White Sox to put José Abreu -- who had driven in a pair of runs earlier in the game -- at the plate as the tying run in the ninth with two on and two out against closer Craig Kimbrel.

Abreu swung through a breaking pitch for the third strike, but he didn’t break immediately from the box as the ball got away from catcher Willson Contreras.

Contreras retrieved the ball on a perfect bounce and threw out Abreu by a comfortable margin at first. The only chance Abreu had to make it close was recognizing the ball got away immediately.

“It wasn't because he wasn't trying to go,” Renteria said. “The question would have been if he stayed at the box when the ball got back to the backstop and didn't give you an effort or something.”

“I was looking for a fastball that pitch, and he threw me the breaking ball,” said Abreu through interpreter Billy Russo. “I was out of balance, and I didn't identify where the ball was right away.”